There is a growing demand for cosmetic procedures which augment soft tissue to enhance facial appearance. The American Society for Aesthetic Plastic Surgery reports nearly 8.3 million aesthetic procedures were performed in 2003, and increase of 20% from the year before. The most common of these procedures are intended to remove facial wrinkles and lines or augment the lips to restore a more youthful appearance.
Botulinum toxin is used to paralyze the small facial muscles around dynamic wrinkles in the forehead and around the eyes. Materials that have been used to smooth non-dynamic wrinkles or augment facial tissues (nasolabial lines, lips, etc.) include injectable soft tissue fillers such as silicone, collagen in a variety of forms and formulations such as Inamed Corporation's CosmoDerm and CosmoPlast, hyaluronic acid derivatives such as Restylene and Hyaloform, and calcium hydroxylapatite microspheres such as Radiance. Autologous fat can also be taken from a donor site by liposuction and then injected in the targeted facial tissue. While these injectable fillers are convenient, and some can even be done as a simple office procedure, the results are temporary and once injected, the filler cannot be removed.
Implanted artificial tissue fillers are well known and are generally placed through surgical incisions. These include ePTFE-based tubes, fibers or sheets, including Gore Subcutaneous Augmentation Material (S.A.M.), Advanta, marketed by Atrium Medical, and Ultrasoft and Softform marketed by Tissue Technologies, now Integra Life Sciences. Surgically implanted tissue fillers can also be derived from biologic sources such as Alloderm from LifeCell Corp. and DuraDerm from Collagensis, Inc.
Surgically implanted fillers have a number of limitations such as prolonged recovery time due to bruising and swelling which is unacceptable to many patients, risk of infection or granuloma formation, erosion, shrinking and migration. Many patients cannot accept the fact the implant is palpable under the skin because it is firmer than the surrounding skin. The implanted fillers may also be difficult to remove, should the patient wish, or a complication arises that demands its removal.
The ideal facial tissue filler would be: completely biocompatible; easy to place through a relatively small needle, as opposed to through a surgical incision; would be permanent but could be removed either at the time of the procedure to allow for re-positioning, or at some time in the future; would have a very low risk of infection or immunologic response; would not expand, contact or migrate over time; would not erode; and would not be noticeable to the patient.
Biocompatible medical devices that have a small enough profile to fit into a catheter, yet self-expand or are made to expand when such a device is released from the distal end of the catheter, are ubiquitous in vascular, cardiovascular and neurovascular intervention. Such devices include various types and configurations of self-expanding or balloon expandable stents, and embolization coils. These devices are often constructed of a metal and can be covered with a polymer such as a sleeve of e-PTFE.
However, there remains a need for a device of a similar nature that can be placed within a non-vascular space such as dermal tissue, which can be enlarged in situ to provide a desired cosmetic or therapeutic result.